Driver fatigue is a very important risk in today's traffic safety. The USA National Highway Traffic Safety Administration conservatively estimates that 100,000 police-reported crashes are the direct result of driver fatigue each year in the USA. This results in an estimated 1,550 deaths, 71,000 injuries, and $12.5 billion in monetary losses each year. The means of predicting the driver fatigue are essential to reduce the loss of human lives, injuries and finally economic losses. A lot of effort in different techniques and approaches are currently undergoing, to provide the technical solutions, which must comply with functional capability to detect the driver fatigue, which is practical to use, can be integrated in the vehicle, and finally which is low-cost and compact enough to be practically deployed by the automotive industry.
The state of the art differentiate between principle approaches: evaluation of the driver behavior in vehicle, such as the movement of the driver's hands on the steering wheel, analysis of the vehicle driver behavior, analysis of the physiological status of the driver, and finally combination of the above principles. In many scientific papers in last two decades the ECG signals were used for investigations related to driver fatigue. Research of sleep behavior scientifically confirmed that the respiratory frequency can be used as a biomarker for probability driven detection of the driver fatigue. In most cases those investigations included ECG devices on human skin, and separately complicated respiratory measurement system on human head. It was also published in different scientific articles that microwave radar sensor, in the frequency range 3-30 GHz, may be used to detect the vital signs. Especially 2.4, 3-10, 24 and 60 GHz vital sign demonstrators have been publicly reported.
The following patents and patent applications published in last several years show the relevance of the topic and the state-of-the-art.
US 2013/0166217 A1, “Method and Device for fatigue detection” recent application combined ambient brightness and activity of the driver to reach the information about fatigue.
US 2008/0074618 A1, “Fatigue detection using encoded light signals”, addresses eye lid movement of the driver to reach information about fatigue.
US 2012/0265080 A1, “Non-contact sensing of physiological signals”, addresses movement of the body by non-contactless means, to reach information about fatigue. The electrode is configured to detect electrical signals from a surface of a subject's body without directly contacting the surface of the subject's body (i.e. via capacitive coupling).
U.S. Pat. No. 8,285,372 B2, “Alertness/drowsiness and cognitive index” addresses method of operation for driver fatigue recognition by using EEG signals obtained from the individual.
DE 102012000629 A1, “Method for detecting tiredness of driver of vehicle, involves transferring automatically detected tiredness affecting data from a mobile device to the vehicle, when the mobile terminal is communicatively coupled to the vehicle” of Volkswagen address the usage of the mobile equipment which detect the fatigue of the driver.
DE 102011104203 A1, “Device for detecting tiredness of driver of motor car, has processing unit for detecting tiredness-characterizing displacement of weight of driver of motor car, and sensor for detecting displacement of weight and arranged in seat surface” of General Motors addresses processing the information from weight sensor incorporated in the driver seat.
DE 102009046913 A1, “Method for detecting fatigue of driver of e.g. lorry during driving, involves evaluating information about steering movement and surrounding information for determining whether information about steering movement indicates fatigue of driver”, of Robert Bosch GmbH involves evaluating information about steering movement and surrounding information for determining whether information about steering movement indicates fatigue of driver.
DE 102012013549 A1, “Method for determining driving state of driver of vehicle, involves obtaining number of activatable vitalization measures to reduce inattention and fatigue for performing manual selection and activation”, considers the video technology for obtaining driver fatigue information.
CN 103230270 A1, “Capacitor electrode for detecting electrocardiogram signals of motorist” is utilizing driver contact with the steering wheel for the capacitor electrode ECG sensor to obtain the fatigue information.
DE 102011113100 A1, “Method for detection of ballistocardlogenic or respiratory-caused movements of person on motor vehicle seat, involves designing sensor as ballistographic sensor for detection of ballistocardiogenic or respiratory-caused movements of person” by Volkswagen involves ballistographic sensor for detection of ballistocardiogenic or respiratory-caused movements of a person, where the sensor are integrated in the driver seats. This is combined with the seat occupancy detection.
WO 2013076018 A1, “Detection of vital parameters by means of an optical sensor on the steering wheel” addresses detection device for detecting at least one vital parameter of a person in a motor vehicle with a steering wheel, comprising a finger sensor device with an optical sensor device, to address the driver fatigue.
CN 102509419 B, “Wireless driver fatigue monitoring device” is published, disclosing wireless monitoring device for driver fatigue, including microwave signal transmission for respiratory conditions detection of the driver, using 24 GHz radio. The system analyses the driver's breathing using wireless signal, and then converts it to a respiratory frequency. This information is compared to a preset threshold value in order to determine the fatigue.